The present invention relates to methods, apparatus and systems for delivering high power laser energy over long distances, while maintaining the power of the laser energy to perform desired tasks. In a particular, the present invention relates to paths, dynamics and parameters of fluid flows used in conjunction with a laser bottom hole assembly (LBHA) for the control and removal of material in conjunction with the creation and advancement of a borehole in the earth by the delivery of high power laser energy to the bottom of a borehole.
The present invention is useful with and may be employed in conjunction with the systems, apparatus and methods that are disclosed in greater detail in U.S. patent application Ser. No. 12/544,136, titled Method and Apparatus for Delivering High Power Laser Energy Over Long Distances, (issued as U.S. Pat. No. 8,511,401), U.S. patent application Ser. No. 12/544,038, titled Apparatus for Advancing a Wellbore using High Power Laser Energy, and U.S. patent application Ser. No. 12/544,094, titled Methods and Apparatus for Delivering High Power Laser Energy to a Surface (issued as U.S. Pat. No. 8,424,617), filed contemporaneously with parent application Ser. No. 12/543,968, the disclosures of which are incorporate herein by reference in their entirety.
In general, boreholes have been formed in the earth's surface and the earth, i.e., the ground, to access resources that are located at and below the surface. Such resources would include hydrocarbons, such as oil and natural gas, water, and geothermal energy sources, including hydrothermal wells. Boreholes have also been formed in the ground to study, sample and explore materials and formations that are located below the surface. They have also been formed in the ground to create passageways for the placement of cables and other such items below the surface of the earth.
The term borehole includes any opening that is created in the ground that is substantially longer than it is wide, such as a well, a well bore, a well hole, and other terms commonly used or known in the art to define these types of narrow long passages in the earth. Although boreholes are generally oriented substantially vertically, they may also be oriented on an angle from vertical, to and including horizontal. Thus, using a level line as representing the horizontal orientation, a borehole can range in orientation from 0° i.e., a vertical borehole, to 90°, i.e., a horizontal borehole and greater than 90° e.g., such as a heel and toe. Boreholes may further have segments or sections that have different orientations, they may be arcuate, and they may be of the shapes commonly found when directional drilling is employed. Thus, as used herein unless expressly provided otherwise, the “bottom” of the borehole, the “bottom” surface of the borehole and similar terms refer to the end of the borehole, i.e., that portion of the borehole farthest along the path of the borehole from the borehole's opening, the surface of the earth, or the borehole's beginning.
Advancing a borehole means to increase the length of the borehole. Thus, by advancing a borehole, other than a horizontal one, the depth of the borehole is also increased. Boreholes are generally formed and advanced by using mechanical drilling equipment having a rotating drilling bit. The drilling bit is extending to and into the earth and rotated to create a hole in the earth. In general, to perform the drilling operation a diamond tip tool is used. That tool must be forced against the rock or earth to be cut with a sufficient force to exceed the shear strength of that material. Thus, in conventional drilling activity mechanical forces exceeding the shear strength of the rock or earth must be applied to that material. The material that is cut from the earth is generally known as cuttings, i.e., waste, which may be chips of rock, dust, rock fibers and other types of materials and structures that may be created by the thermal or mechanical interactions with the earth. These cuttings are typically removed from the borehole by the use of fluids, which fluids can be liquids, foams or gases.
In addition to advancing the borehole, other types of activities are performed in or related to forming a borehole, such as, work over and completion activities. These types of activities would include for example the cutting and perforating of casing and the removal of a well plug. Well casing, or casing, refers to the tubulars or other material that are used to line a wellbore. A well plug is a structure, or material that is placed in a borehole to fill and block the borehole. A well plug is intended to prevent or restrict materials from flowing in the borehole.
Typically, perforating, i.e., the perforation activity, involves the use of a perforating tool to create openings, e.g. windows, or a porosity in the casing and borehole to permit the sought after resource to flow into the borehole. Thus, perforating tools may use an explosive charge to create, or drive projectiles into the casing and the sides of the borehole to create such openings or porosities.
The above mentioned conventional ways to form and advance a borehole are referred to as mechanical techniques, or mechanical drilling techniques, because they require a mechanical interaction between the drilling equipment, e.g., the drill bit or perforation tool, and the earth or casing to transmit the force needed to cut the earth or casing.
There is a need for the removal of cuttings or waste material that are created as the borehole is advanced, or as other cutting or material removal activities take place, as a result of the laser beam illumination of material. There is further a need for keeping the laser path clear, or at a minimum sufficiently free of debris or material to prevent adverse effects on, or loss of power of, the laser beam. The present invention addresses and provides solutions to these and other needs in the drilling arts by providing, among other things, paths, dynamics and parameters of fluid flows used in conjunction with laser drilling or an LBHA for the control and removal of material in conjunction with the creation and advancement of a borehole in the earth by the delivery of high power laser energy to the bottom of a borehole.